Radioreceiver



Oct. 30, 1934. O. ROOSENSTElN 1,978,478

RADIORECEIVER Filed June 11, 193?.

c wiqurmw l INVENTOR HANS o. OOSEN'STEIN BY g ATTORNEY,

equation 55 1 of the amplifier tube 7.

Patented Get. 30, 1934 UNlTEDSTATES PATENT orrics RADIORECEIVER Hans 0. Roosenstein, Berlin, Germany, assignor to Telefunken Gesellschaft fiir Drahtlose Telegraphie m. b. H., Berlin, Germany, a corporation of Germany Application June 11, 1932, Serial No. 616,600 In Germany June 17, 1931 5 Claims. (01. 250-27) In copending patent application Serial No. 615,647 filed June 6, 1932, a rectifier circuit has been disclosed whereby elimination of fading in reception is possible by the use of a steadily acting rectifier stage having a logarithmic rectifier characteristic.

According to the present invention the rectifier stage consists of the combination of a rectifier of any desired type at all and a suitably distorted amplifier.

Let E be the field (intensity) of an incoming non-modulated signal, and the direct current resulting from rectification be represented by the rectifier characteristic which satisfies the The characteristic curve of the amplifier for rectified oscillations may further be represented by where J, is the amplified current (strength).

Now, it is possible to choose the functions ,u and f in such a manner that this latter equation 12,51 assumes the character J =log nat E+constant Fundamentally speaking, this condition can be satisfied an infinite number of ways.

As the simplest example there will be chosen the case where the rectifier characteristic is linear, whereas amplification follows a logarithmic law:

Jt=B log nat Jg' B log nat E+B log nat A.

This solution leads to a technically simple embodiment, the basic principle of which is shown in the accompanying drawing.

Referring to the drawing in more detail, 1 is the rectifier tube in which rectification is rendered linear by application of the well-known audion principle, involving the use of a blocking condenser 2 and resistance 3, inside as large a r t'? range as possible. The mean value of the grid potential of tube 1 and therefore also the mean value of the voltage drop across resistance 4 are, therefore, linear functions of the field intensity of the incoming signals. The condenser 5 serves Ias a short-circuit for the radio frequency potential. The entire rectified current, i. e., its audio frequency component and its D. C. component added together, is fed by way of an extremely high resistance 6 (say, 100 megohms) to the grid The amplifier tube operates inside the range of negative grid potential in which, as is well known, within wide ranges of the grid current i there holds good the law:

(where'e the base of nat. log, 'Ug the grid potential, A and B constants). The resistance 6 shall be assumed to have such a high value R that it is practically governing only for the strength of the current i Furthermore, the branch F is so regulated that between the points E and F no direct current potential differences will exist when no signal impinges upon the receiver. A signal causes a rise of potential 1: of E compared with F, and the ensuing grid current, in the light of what has been pointed out before, is calculated to be approximately Expressed in words, this equation states that the grid potential of the amplifier tube is the desired logarithmic function of the rectified potential and thus of the incoming radio frequency field.

I claim:

1. A high frequency network, simulating a rectifier stage having a logarithmic rectifier characteristic, comprising a leaky grid detector having a linear rectification characteristic over a wide range of input energy, an amplifier, an impedance in the anode circuit of the detector for developing the detector output potential, an impedance coupling the anode circuit of the detector to the grid circuit of the amplifier, said coupling impedance having a relatively high resistive value with respect to said first impedance, said amplifier having a grid voltage-grid current characteristic such that the amplifier grid potential is a logarithmic function of the potential developed across the first impedance.

2. A high frequency network, simulating a rectifier stage having a logarithmic rectifier characteristic, comprising a leaky grid detector having a linear rectification characteristic over a wide range of input energy, an amplifier, an impedance in the anode circuit of the detector for developing the detector output potential, an impedance coupling the anode circuit of the detector to the grid circuit of the amplifier, said coupling impedance having a relatively high resistive value of the order of 100 megohms, said amplifier having a grid voltage-grid current characteristic such that the amplifier grid potential is a logarithmic function of the potential developed across the first impedance.

3. A high frequency network, simulating a rectifier stage having a logarithmic rectifier characteristic, comprisin a leaky grid detector having a linear rectification characteristic over a Wide range of input energy, an amplifier, an impedance in the anode circuit of the detector for developing the detector output potential, an impedance coupling the anode circuit of the detector to the grid circuit of the amplifier, said coupling impedance having a relatively high resistive value with respect to said first impedance, said amplifier having a grid voltage-grid current characteristic such that the amplifier grid potential is a logarithmic function of the potential developed across the first impedance and both said impedances being resistors.

4. A high frequency network, simulating a rec- .tifier stage having a logarithmic rectifier characteristic, comprising a leaky grid detector having a linear rectification characteristic over a Wide range of input energy, an amplifier, an impedance in the anode circuit of the detector for developing the detector output potential, an

impedance coupling the anode circuit of the detector to the grid circuit of the amplifier, said coupling impedance having a relatively high resistive value with respect to said first impedance, said amplifier having a grid voltage-grid current characteristic such that the amplifier grid potential is a logarithmic function of the potential developed across the first impedance, and a path of low impedance to high frequency currents between the anode and cathode of the detector.

5. A high frequency network, simulating a rectifier stage having a logarithmic rectifier characteristic, comprising a detector tube having a resistor in its anode circuit for developing the detector output potential, an amplifier tube, a resistor coupling the grid of said amplifier to the anode side of the first resistor, said coupling resistor having arelatively higher magnitude than the first resistor, said amplifier having a grid voltage-grid current characteristic such that in combination with the grid voltage-anode current characteristic of the detector tube the amplifier grid potential is a logarithmic function of the potential developed across the first resistor.

HANS O. ROOSENSTEIN.

IUD 

